Figure 2.

Fibrin polymerisation. Thrombin mediated cleavage of fibrinopeptides FpA and FpB initiates fibrinogen conversion into fibrin. Cleavage of FpA and FpB from the N-termini of Aα and Bβ respectively exposes knob ‘A’ and ‘B’, which in turn interact with complementary pockets ‘a’ and ‘b’ located on the γ- and β- nodules on a neighbouring fibrin monomer. FpB cleavage occurs at slower rate compared to FpA, and this is followed by the release of the αC domains allowing αC:αC interactions and lateral aggregation. Activation of FXIII by thrombin facilitates FXIII-mediated interactions between glutamate (Glu) residues on the γ chain and lysine (Lys) residues on the Aα chain through ε-(γ-glutamyl)-lysyl crosslinks.